The purpose of this study is to measure styrene, stryene oxide, benzene, benzene oxide or their products in the blood. Workers in the reinforced plastics industry are exposed to relatively large amounts of styrene and petroleum workers are exposed to relatively large amounts of benzene. We are conducting other studies of such workers to determine how much of these chemicals are in their blood. Because small amounts of styrene, styrene oxide, benzene and benzene oxide may be present in everyday life, in foods for example, we also want to determine the natural background levels of these substances in the blood of people without occupational exposure to styrene and benzene. We would also like to determine if these low background levels are related to DNA damage in the blood and how well the blood metabolizes these chemicals.